Multi-level skimming of multimedia content using playlists

ABSTRACT

A skimmed or preview version of multimedia content is provided to a client computer by a server computer using playlists. The skimmed version of multimedia content can be presented to a user of a client computer in less time than presenting the entire multimedia content would require. The server computer maintains skimming information that identifies particular segments of the multimedia content corresponding to the skimmed version. The server computer uses the skimming information to generate a playlist, which in turn is used by the server computer to access the appropriate segments of the multimedia content and provide the segments to the client computer.

RELATED APPLICATIONS

This is a continuation of application Ser. No. 09/498,439, filed Feb. 4,2000, entitled “Multi-Level Skimming of Multimedia Content UsingPlaylists”, which is hereby incorporated by reference herein.

TECHNICAL FIELD

This invention relates to networked client/server systems and to methodsof streaming and rendering multimedia content in such systems. Moreparticularly, the invention relates to generating, maintaining andproviding multiple skimmed versions of multimedia content usingplaylists.

BACKGROUND OF THE INVENTION

Multimedia streaming—the continuous delivery of synchronized media datalike video, audio, text, and animation—is a critical link in the digitalmultimedia revolution. Today, streamed media is primarily about videoand audio, but a richer, broader digital media era is emerging with aprofound and growing impact on the Internet and digital broadcasting.

Synchronized media means multiple media objects that share a commontimeline. Video and audio are examples of synchronized media—each is aseparate data stream with its own data structure, but the two datastreams are played back in synchronization with each other. Virtuallyany media type can have a timeline. For example, an image object canchange like an animated .gif file, text can change and move, andanimation and digital effects can happen over time. This concept ofsynchronizing multiple media types is gaining greater meaning andcurrency with the emergence of more sophisticated media compositionframeworks implied by MPEG-4, Dynamic HTML, and other media playbackenvironments.

The term “streaming” is used to indicate that the data representing thevarious media types is provided over a network to a client computer on areal-time, as-needed basis, rather than being pre-delivered in itsentirety before playback. Thus, the client computer renders streamingdata as it is received from a network server, rather than waiting for anentire “file” to be delivered.

In comparison to text-based or paper-based presentations, multimediapresentations can be very advantageous. Synchronized audio/visualpresentations, for example, are able to capture and convey many subtlefactors that are not perceivable from paper-based documents. Even whenthe content is a spoken presentation, an audio/visual recording capturesgestures, facial expressions, and various speech nuances that cannot bediscerned from text or even from still photographs.

Although streaming multimedia content compares favorably with textualcontent in most regards, one disadvantage is that it requiressignificant time for viewing. It cannot be “skimmed” like textualcontent. Thus, a “summarized” or “skimmed” version of the multimediacontent would be very helpful.

Various technologies are available for “summarizing” or “previewing”different types of media content. For example, technology is availablefor removing pauses from spoken audio content. Audio content can also besummarized with algorithms that detect “important” parts of the contentas identified by pitch emphasis. Similarly, techniques are available forremoving redundant or otherwise “unimportant” portions or frames ofvideo content. Similar schemes can be used with other types of mediastreams, such as animation streams and script streams.

Although such previewing techniques are available, these techniquestypically require a significant amount of processing power to beperformed and a significant amount of time to be completed. Suchconstraints make it difficult to generate previews “on the fly” as thedata is being streamed to its destination.

One solution is to pre-generate and store a “preview” version of themultimedia content, thereby reducing the impact of “on the fly”calculations. However, generating and storing such a preview versioncreates a storage problem. The multimedia content itself frequentlyrequires a significant amount of storage space. By storing an additionalpreview version of the multimedia content, the storage spacerequirements are increased further, thereby generating significantconstraints on the media storage device. This problem is exacerbated ifmultiple preview versions are generated and stored.

The invention described below addresses these disadvantages ofpreviewing multimedia content, providing an improved way to generate andmaintain such preview content.

SUMMARY OF THE INVENTION

A system includes a multimedia server computer that can providemultimedia content, as well as skimmed versions of the multimediacontent, to one or more client computers. A skimmed version of themultimedia content is a preview or summary of the multimedia contentthat can be presented to a user in less time than presenting the entiremultimedia content would require.

One or more skimmed versions of multimedia content are provided by theserver computer using playlists. Skimming information is maintained bythe server computer for each skimmed version, the skimming informationidentifying particular segments of the multimedia content for aparticular skimmed version. The server computer (or alternatively theclient computer) uses the skimming information to generate a playlist ofmultimedia segments of the multimedia content. Rather than maintainingthe actual segments of the multimedia content, the playlist identifiessegments of the multimedia content. The playlist is used by the servercomputer to access the appropriate segments of the multimedia contentand provide such segments to the client computer(s).

Additionally, a user can select different skimmed versions that he orshe will be presented with. The user can make such selections prior toor during presentation of a skimmed version of the multimedia content.Upon selecting a different skimmed version, one of the server computeror the client computer generates a playlist for the newly selectedskimmed version and determines a location in the new playlist thatcorresponds to the location being presented in the current playlist.Presentation of the new skimmed version then begins at the correspondinglocation in the new playlist.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and notlimitation in the figures of the accompanying drawings. The same numbersare used throughout the figures to reference like components and/orfeatures.

FIG. 1 shows a client/server network system and environment inaccordance with the invention

FIG. 2 shows a general example of a computer that can be used as aserver or client in accordance with the invention.

FIG. 3 is an exemplary block diagram showing the generation of skimminglevel information for multimedia content.

FIG. 4 illustrates a multimedia file of FIG. 3 in more detail.

FIG. 5 is a flowchart illustrating an exemplary process for generatingskimming level information in accordance with the invention.

FIG. 6 illustrates exemplary client and server computers in which theplaylist for the skimmed version is generated at the server computer.

FIG. 7 illustrates alternate client and server computers in which theplaylist for the skimmed version is generated at the client computer.

FIG. 8 is a flowchart illustrating exemplary steps in presentingmultimedia segments corresponding to a skimming level to a user inaccordance with the invention.

FIG. 9 is a flowchart illustrating exemplary steps in changing skimminglevels in accordance with the invention.

FIG. 10 shows one implementation of a graphical user interface windowthat displays multimedia content at a client computer.

FIG. 11 shows another implementation of a graphical user interfacewindow that displays multimedia content at a client computer.

DETAILED DESCRIPTION

General Network Structure

FIG. 1 shows a client/server network system and environment inaccordance with the invention. Generally, the system includes one ormore network server computers 102, and multiple (n) network clientcomputers 104. The computers communicate with each other over a datacommunications network. The communications network in FIG. 1 comprises apublic network 106 such as the Internet. The data communications networkmight also include local-area networks and private wide-area networks.

Multimedia server 102 has access to streaming media content in the formof different media streams. These media streams can be individual mediastreams (e.g., audio, video, graphical, etc.), or alternativelycomposite media streams including multiple such individual streams. Somemedia streams might be stored as files 108 in a database or other filestorage system, while other media streams 110 might be supplied to theserver on a “live” basis from other data source components throughdedicated communications channels or through the Internet itself.

Multimedia server 102 also has access to data or information identifyingdifferent skimmed versions of the media streams. This “skimming”information identifies different segments of media streams that are partof a particular skimmed version of that stream. Multiple skimmingversions or “skimming levels” can be maintained for each media stream.By using the skimming information to identify portions of media streams,storage space requirements are reduced because the data of the mediastreams need not be duplicated.

In the discussions to follow, the multimedia content available to theclient computers 104 is discussed as being streaming media. However, itshould be noted that the invention can also be used with “pre-delivered”media rather than streaming media, such as media previously stored atthe client computers 104 via the network 106, via removable magnetic oroptical disks, etc.

Streaming Media

In this discussion, the term “composite media stream” describessynchronized streaming data that represents a segment of multimediacontent. The composite media stream has a timeline that establishes thespeed at which the content is rendered. The composite media stream canbe rendered to produce a plurality of different types ofuser-perceivable media, including synchronized audio or sound, videographics or motion pictures, animation, textual content, command scriptsequences, or other media types that convey time-varying information orcontent in a way that can be sensed and perceived by a human. Acomposite media stream comprises a plurality of individual media streamsrepresenting the multimedia content. Each of the individual mediastreams corresponds to and represents a different media type and each ofthe media streams can be rendered by a network client to produce auser-perceivable presentation using a particular presentation medium.The individual media streams have their own timelines, which aresynchronized with each other so that the media streams can be renderedsimultaneously for a coordinated multimedia presentation. The individualtimelines define the timeline of the composite stream.

There are various standards for streaming media content and compositemedia streams. “Advanced Streaming Format” (ASF) is an example of such astandard, including both accepted versions of the standard and proposedstandards for future adoption. ASF specifies the way in which multimediacontent is stored, streamed, and presented by the tools, servers, andclients of various multimedia vendors. ASF provides benefits such aslocal and network playback, extensible media types, component download,scalable media types, prioritization of streams, multiple languagesupport, environment independence, rich inter-stream relationships, andexpandability. Further details about ASF are available from MicrosoftCorporation of Redmond, Wash.

Regardless of the streaming format used, an individual data streamcontains a sequence of digital data sets or units that are renderedindividually, in sequence, to produce an image, sound, or some otherstimuli that is perceived by a human to be continuously varying. Forexample, an audio data stream comprises a sequence of sample values thatare converted to a pitch and volume to produce continuously varyingsound. A video data stream comprises a sequence of digitally-specifiedgraphics frames that are rendered in sequence to produce a movingpicture.

Typically, the individual data units of a composite media stream areinterleaved in a single sequence of data packets. Various types of datacompression might be used within a particular data format to reducecommunications bandwidth requirements.

The sequential data units (such as audio sample values or video frames)are associated with both delivery times and presentation times, relativeto an arbitrary start time. The delivery time of a data unit indicateswhen the data unit should be delivered to a rendering client. Thepresentation time indicates when the value should be actually rendered.Normally, the delivery time of a data unit precedes its presentationtime.

The presentation times determine the actual speed of playback. For datastreams representing actual events or performances, the presentationtimes correspond to the relative times at which the data samples wereactually recorded. The presentation times of the various differentindividual data streams are consistent with each other so that thestreams remain coordinated and synchronized during playback.

Exemplary Computer Environment

In the discussion below, the invention will be described in the generalcontext of computer-executable instructions, such as program modules,being executed by one or more conventional personal computers.Generally, program modules include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types. Moreover, those skilled in theart will appreciate that the invention may be practiced with othercomputer system configurations, including hand-held devices,multiprocessor systems, microprocessor-based or programmable consumerelectronics, network PCs, minicomputers, mainframe computers, and thelike. In a distributed computer environment, program modules may belocated in both local and remote memory storage devices.

FIG. 2 shows a general example of a computer 130 that can be used as aserver or client in accordance with the invention. Computer 130 is shownas an example of a computer that can perform the functions of a servercomputer 102 or a client computer 104 of FIG. 1.

Computer 130 includes one or more processors or processing units 132, asystem memory 134, and a bus 136 that couples various system componentsincluding the system memory 134 to processors 132.

The bus 136 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. The system memory includes readonly memory (ROM) 138 and random access memory (RAM) 140. A basicinput/output system (BIOS) 142, containing the basic routines that helpto transfer information between elements within computer 130, such asduring start-up, is stored in ROM 138. Computer 130 further includes ahard disk drive 144 for reading from and writing to a hard disk, notshown, a magnetic disk drive 146 for reading from and writing to aremovable magnetic disk 148, and an optical disk drive 150 for readingfrom or writing to a removable optical disk 152 such as a CD ROM orother optical media. The hard disk drive 144, magnetic disk drive 146,and optical disk drive 150 are connected to the bus 136 by an SCSIinterface 154 or some other appropriate interface. The drives and theirassociated computer-readable media provide nonvolatile storage ofcomputer readable instructions, data structures, program modules andother data for computer 130. Although the exemplary environmentdescribed herein employs a hard disk, a removable magnetic disk 148 anda removable optical disk 152, it should be appreciated by those skilledin the art that other types of computer readable media which can storedata that is accessible by a computer, such as magnetic cassettes, flashmemory cards, digital video disks, random access memories (RAMs) readonly memories (ROM), and the like, may also be used in the exemplaryoperating environment.

A number of program modules may be stored on the hard disk, magneticdisk 148, optical disk 152, ROM 138, or RAM 140, including an operatingsystem 158, one or more application programs 160, other program modules162, and program data 164. A user may enter commands and informationinto computer 130 through input devices such as keyboard 166 andpointing device 168. Other input devices (not shown) may include amicrophone, joystick, game pad, satellite dish, scanner, or the like.These and other input devices are connected to the processing unit 132through an interface 170 that is coupled to the bus 136. A monitor 172or other type of display device is also connected to the bus 136 via aninterface, such as a video adapter 174. In addition to the monitor,personal computers typically include other peripheral output devices(not shown) such as speakers and printers.

Computer 130 operates in a networked environment using logicalconnections to one or more remote computers, such as a remote computer176. The remote computer 176 may be another personal computer, a server,a router, a network PC, a peer device or other common network node, andtypically includes many or all of the elements described above relativeto computer 130, although only a memory storage device 178 has beenillustrated in FIG. 2. The logical connections depicted in FIG. 2include a local area network (LAN) 180 and a wide area network (WAN)182. Such networking environments are commonplace in offices,enterprise-wide computer networks, intranets, and the Internet. In thedescribed embodiment of the invention, remote computer 176 executes anInternet Web browser program such as the “Internet Explorer” Web browsermanufactured and distributed by Microsoft Corporation of Redmond, Wash..

When used in a LAN networking environment, computer 130 is connected tothe local network 180 through a network interface or adapter 184. Whenused in a WAN networking environment, computer 130 typically includes amodem 186 or other means for establishing communications over the widearea network 182, such as the Internet. The modem 186, which may beinternal or external, is connected to the bus 136 via a serial portinterface 156. In a networked environment, program modules depictedrelative to the personal computer 130, or portions thereof, may bestored in the remote memory storage device. It will be appreciated thatthe network connections shown are exemplary and other means ofestablishing a communications link between the computers may be used.

Generally, the data processors of computer 130 are programmed by meansof instructions stored at different times in the variouscomputer-readable storage media of the computer. Programs and operatingsystems are typically distributed, for example, on floppy disks orCD-ROMs. From there, they are installed or loaded into the secondarymemory of a computer. At execution, they are loaded at least partiallyinto the computer's primary electronic memory. The invention describedherein includes these and other various types of computer-readablestorage media when such media contain instructions or programs forimplementing the steps described below in conjunction with amicroprocessor or other data processor. The invention also includes thecomputer itself when programmed according to the methods and techniquesdescribed below. Furthermore, certain sub-components of the computer maybe programmed to perform the functions and steps described below. Theinvention includes such sub-components when they are programmed asdescribed. In addition, the invention described herein includes datastructures, described below, as embodied on various types of memorymedia.

For purposes of illustration, programs and other executable programcomponents such as the operating system are illustrated herein asdiscrete blocks, although it is recognized that such programs andcomponents reside at various times in different storage components ofthe computer, and are executed by the data processor(s) of the computer.

Generating Skimmed Versions

Multiple preview or skimmed versions of multimedia content can becreated, such versions being referred to as being different “skimminglevels”. Each of these different skimming levels provides a differentlevel of detail of the multimedia content, and thus typically includes adifferent total presentation time. For example, a first skimming levelmay represent little of the original multimedia content and have apresentation time of 15 minutes rather than the 2 hour presentation timeof the entire multimedia content. A second skimming level may representmore of the original multimedia content and have a presentation time of1 hour.

FIG. 3 is an exemplary block diagram showing the generation of skimminglevel information for multimedia content. Multimedia content 200 isreceived by a skimming generator 202. Skimming generator 202 can beimplemented in hardware or software, such as a software programexecuting on a computer 130 of FIG. 2. Additionally, skimming generator202 can be implemented in server computer 102 of FIG. 1, oralternatively in another computer (not shown) either coupled to orindependent of network 106. Multimedia content 200 can be provided toskimming generator 202 in a variety of different manners, such asstreaming of a live presentation, streaming of a data file,“pre-delivery” of a data file (e.g., on a CD-ROM or transferred vianetwork 106 of FIG. 1), etc.

Skimming generator 202 processes the multimedia content 200 to createmultiple (m) skimming levels 204, 206, and 208 corresponding to themultimedia content 200. Skimming generator 202 separates the multimediacontent into multiple segments and generates the multiple skimminglevels 204-208 using various combinations of these segments. Each of theskimming levels 204-208 comprises a different set of these multimediasegments. Skimming generator 202 uses any of a variety of conventionalsummarizing or previewing technologies (e.g., pitch analysis to detectimportant parts of audio content and similar techniques to identifyimportant parts of video content) to generate the skimming levels204-208.

The results of the various previewing techniques for different streamsmay identify different portions of the multimedia content that are moreimportant. In the illustrated example, this situation is resolved byusing a composite scoring method to identify which segments are moreimportant (and thus are kept as part of the skimmed version), and whichsegments are less important (and thus are not included as part of theskimmed version).

Alternatively, the results of one of the previewing techniques on asingle data stream may be used to identify which segments are to bedropped. For example, a single data stream (e.g., the audio stream) maybe evaluated, with the results of that evaluation being used to identifywhich segments of the audio stream (and corresponding segments of thevideo and other streams) are dropped without any evaluation of thecorresponding segments of the other streams.

Skimming information for each of the skimming levels 204-208 is thenstored in multimedia file 210. This skimming information can be, forexample, identifies of particular segments of the multimedia content,importance rankings for each of multiple segments of the multimediacontent, etc. Additionally, an indication of the total number m ofskimming levels is also stored in multimedia file 210.

In the illustrated example, the multimedia content 200 is received byskimming generator 202 as multimedia file 210. Thus, skimming generator202 stores the skimming information for each of the skimming levels204-208 back into the same data file as the multimedia content 200 isstored in.

In the example illustrated in FIG. 3, multimedia file 210 is an ASFfile. Multimedia file 210 includes a header portion 212 and a dataportion 214. Header portion 212 contains data representing variouscontrol and identifying information regarding the multimedia file 210.Data portion 214 contains the multimedia content as well as the skimminginformation for each of the skimming levels 204-208.

The skimming level generation process identifies different segments ofthe multimedia content 200 for each of the different levels 204-208.Skimming generator 202 then stores data identifying these differentsegments in the data portion 214 of multimedia file 210. Alternatively,a linear separation technique could be used to delineate the segments,such as each segment being a 5-second portion of the multimedia content.

Alternatively, rather than storing identifiers of particular segments ofthe multimedia content, skimming generator 202 could generate particular“rankings” for each segment of the multimedia content. These rankingsare generated using the conventional summarizing or previewingtechnologies to identify which portions of the multimedia content aremore important than which others or alternatively could be generatedmanually. The different portions are then assigned a particular rank orweight (e.g., “high”, “medium”, and “low”; or any of an infinite numberof rankings (such as real number values between zero and one)). Theserankings can then be subsequently used to dynamically identify whichsegments should be presented for a particular skimming level.

Additionally, skimming generator 202 identifies the relationship betweenthe presentation timeline of the original multimedia content and thesegments identified by the skimming information. This relationship maybe stored as an additional stream in multimedia file 210, oralternatively as one or more index tables associated with multimediafile 210. The relationship is a mapping of presentation times of theskimmed version to the original multimedia content, indicating for anypresentation time of the skimmed version, what the correspondingpresentation time of the original multimedia content is. For example,the data 35 seconds into the skimmed version may correspond to 120seconds into the original multimedia content. This stored relationshipthus allows the server (or client) computer, during subsequent playbackof a skimmed version, to identify the current presentation point withrespect to the original multimedia content. A similar mapping ismaintained for presentation times of the original multimedia content tolocations of the skimmed version (e.g., presentation times, byte offsetsinto the skimmed stream, segment identifiers, etc.).

FIG. 4 illustrates a multimedia file 210 in more detail. Multimedia file210 includes header portion 212 containing various control andidentifying information regarding the multimedia file 210. Headerportion 212 includes data identifying each of the streams in dataportion 214, and optionally may include the number of different skimmedversions maintained in data portion 214. Skimming information for eachskimmed version is maintained as a stream in data portion 214, referredto as a “skimming stream”.

Data portion 214 includes data representing multiple (x) streams 220,222, 224, 226, and 228. Streams 220-228 include media stream data forthe multimedia content, such as audio data and video data of a compositemedia stream, as well as skimming streams that include skimminginformation for the multimedia content.

In the illustrated example, streams 224 and 226 are skimming streamsthat include “markers” (e.g., time ranges) used to identify the segmentsof the multimedia content. The markers can be used to generate a“playlist” identifying particular segments of the multimedia contentthat are to be provided for the corresponding skimming level. A playlistincludes a reference to the multimedia content, as well as start and endtimes for one or more segments of the multimedia content. Alternatively,a skimming stream may include rankings or weights for each of multiplesegments of the multimedia content.

In the illustrated playlists of FIG. 4, the segments are identified bystart and end times corresponding to the timeline of the originalmultimedia content. Thus, the playlist 230 identified by stream 224indicates the first five seconds (0-5) of the multimedia content, aswell as the seventh through ninth seconds (7-9), seventeenth throughtwenty-second seconds (17-22), thirty-seventh through forty-sixthseconds (37-46), fifty-second through sixty-first seconds (52-61), andseventy-second through seventy-seventh seconds (72-77) of the multimediacontent. Similarly, the playlist 232 identified by stream 226 indicatesthe first four seconds (0-4) of the multimedia content, as well as thetwenty-second through twenty-seventh seconds (22-27), thirty-secondthrough thirty-ninth seconds (32-39), and fifty-second throughfifty-seventh seconds (52-57) of the multimedia content.

FIG. 5 is a flowchart illustrating an exemplary process for generatingskimming level information in accordance with the invention. The processof FIG. 5 is implemented by skimming generator 202 of FIG. 3, and may beperformed in software. FIG. 5 is described with additional reference tocomponents in FIGS. 3 and 4.

Initially, multimedia content is received by skimming generator 202(step 250). Skimming generator 202 then determines which segments of themultimedia content correspond to a skimming level (step 252). Asdiscussed above, the generation of different segments can beaccomplished using any of a variety of conventional previewingtechniques.

Skimming generator 202 also stores skimming information identifying thesegments determined in step 252 as a stream of multimedia file 210corresponding to the multimedia content (step 254). Skimming generator202 then checks whether additional skimming levels are to be generated(step 256). The number of skimming levels and their level of detail canbe pre-programmed into skimming generator 202, or alternatively can bemanually input by a user.

Skimmed Version Presentation

When providing a skimmed version of the multimedia content to a user,server computer 102 of FIG. 1 accesses multimedia file 210 of FIG. 4 forthe stream 220-228 corresponding to the requested skimming level. Servercomputer 102 then generates a playlist for that stream that identifieswhich of the segments of the multimedia content are to be provided tothe client as the skimmed version. Alternatively, the client computercould generate the playlist.

FIG. 6 illustrates exemplary client and server computers in which theplaylist for the skimmed version is generated at the server computer.Client computer 104 includes a multimedia player 280 that provides auser interface (UI) allowing a user to be presented with streamingmultimedia content. The multimedia player 280 may be incorporated intothe operating system or run as a separate, self-contained application.In either case, the multimedia player operates in a graphical userinterface windowing environment such as provided by the “WINDOWS” brandof operating systems, available from Microsoft Corporation of Redmond,Wash.

Multimedia player 280 communicates with a multimedia presentation module282 of server computer 102. Multimedia presentation module 282 streamsthe multimedia content to multimedia player 280 for presentation to theuser. Multimedia presentation module 282 can stream the entiremultimedia content to multimedia player 280 for presentation.Additionally, multimedia presentation module 282 can distinguish betweenstreams of multimedia content and streams that contain skimminginformation. Multimedia presentation module 282 uses the skimminginformation to transmit a skimmed version of the multimedia content tothe multimedia player 280 as well.

Multimedia presentation module 282 includes a skimming module 284 and alocation identifier module 286. Skimming module 284 controls theprovision of skimming level options to the user, allowing the user toselect (via the interface of multimedia player 280) a skimmed versionfor presentation. Additionally, skimming module 284 also providesmultimedia presentation module 282 with the control to access skimminginformation and provide the segment(s) of the multimedia contentcorresponding to the skimming information to client computer 104.

In the illustrated example, skimming module 284 accesses the skimminginformation (e.g., in multimedia file 210 of FIG. 4) corresponding to auser-selected skimming level. Skimming module 284 uses this informationto generate a playlist for the skimming level. Multimedia presentationmodule 282 uses the playlist generated by skimming module 284 toidentify which segments of the multimedia content to provide to theclient computer 104 as the selected skimmed version of the multimediacontent. Alternatively, rather than comprising skimming information fromwhich a playlist is generated, the stream in multimedia file 210 couldcomprise a playlist that can be accessed by skimming module 284 “as is”,without requiring any additional generating step.

Alternatively, in situations where the skimming information is a rankfor each segment of the multimedia content, skimming module 284 uses therankings to generate an appropriate playlist. Skimming module 284 uses auser-selected skimming level as a threshold for generating the playlist.For example, skimming module 284 includes in the playlist any segmentshaving a ranking equal to or greater than the threshold.

A user, through the interface provided by multimedia player 280, is ableto select different skimmed versions by selecting a different skimminglevel. This selection can occur prior to being presented with a skimmedversion and/or while being presented with a skimmed version.

When a user changes the skimming level, multimedia player 280 provides,to multimedia presentation module 282, information identifying thecurrent presentation time of the multimedia segment being provided tothe user. This current time information could be a reference to theoriginal multimedia content (e.g., 36 minutes and 20 seconds into theoriginal multimedia content), or alternatively an identification of thecurrent segment of the skimmed version being presented and an offsetinto that segment (e.g., five seconds into the third segment of theskimmed version).

Location identifier module 286 uses the information provided bymultimedia player 280 (either current presentation time or currentsegment and offset) to determine a new location in the playlist of thenewly selected skimming level. As discussed above, a mapping of eachskimmed version to the original multimedia presentation is part of (orstored separately but corresponding to) the multimedia file 210 thatincludes the skimming information. Using these mappings, locationidentifier module 286 is able to identify the location in the newskimmed version to which the current location of the current skimmedversion corresponds.

Location identifier module 286 identifies the location in the newplaylist by accessing the mapping for the current skimmed version usingthe current location in the current skimmed version. The mapping (e.g.,an index table) identifies a location in the original multimedia contentthat corresponds to the current location in the current skimmed version.The identified location from the original multimedia content is thenused to access the mapping for the new skimmed version, which identifiesa location in the new skimmed version that corresponds to the identifiedlocation of the original multimedia content, and thus to the currentlocation in the current skimmed version.

Alternatively, additional mappings can be maintained that alleviate thenecessity for such a “two-step” lookup process. Direct skimmed versionto skimmed version mappings can be generated and maintained (either byserver 102 or by skimming generator 202 of FIG. 3) that map locations inone skimmed version to corresponding locations of other skimmedversions.

FIG. 7 illustrates alternate client and server computers in which theplaylist for the skimmed version is generated at the client computer.Client computer 104 includes a multimedia player 280 that provides aninterface for the user to be presented with streaming multimediacontent. Multimedia player 280 communicates with a multimediapresentation module 288 of server computer 102. Multimedia presentationmodule 288 streams the multimedia content to multimedia player 280 forpresentation to the user. Multimedia presentation module 288 can streamthe entire multimedia content to multimedia player 280 for presentation,or alternatively a skimmed version(s) of the multimedia content.

Multimedia presentation module 288 includes a skimming module 290 thatcontrols the provision of skimming level options to the user. Skimmingmodule 290 allows the user to select (via the interface of multimediaplayer 280), a skimmed version for presentation. Skimming module 290also provides the skimming information corresponding to the multimediacontent to playlist generator 292 of client 104. Multimedia player 280communicates a user-selection of a skimming level to playlist generator292, which in turn uses the skimming information to generate a playlistfor the skimming level. This generated playlist is transferred tomultimedia presentation module 288 of server 102, which in turn uses thegenerated playlist to identify which segments of the multimedia contentto provide to the client computer 104 as the selected skimming versionof the multimedia content.

Additionally, a user is able, through the interface provided bymultimedia player 280, to change the skimmed version he or she is beingpresented with. The user can select an initial skimming level and/orchange the current skimming level while being presented with a skimmedversion. When a user changes the skimming level, location identifiermodule 294 determines the proper location within the playlist of thenewly selected skimming level.

When a user changes the skimming level, multimedia player 280 provides,to location identifier module 294, information identifying the currentpresentation time of the multimedia segment being provided to the user.Location identifier module 294 uses this information to determine a newlocation in the playlist of the newly selected skimming level in amanner analogous to location identifier module 286 of FIG. 6.

FIG. 8 is a flowchart illustrating exemplary steps in presentingmultimedia segments corresponding to a skimming level to a user inaccordance with the invention. The steps on the left side of FIG. 8 areimplemented by client computer 104 of FIG. 6, and the steps on the rightside of FIG. 8 are implemented by server computer 102. The steps of FIG.8, on both client and server computers, may be performed in software.FIG. 8 is described with additional reference to components in FIG. 6.

Initially, the client computer 104 receives a user request formultimedia content (step 302). The request can be initiated by the userin any of a variety of conventional manners, such as selection of amultimedia title in a graphical user interface (GUI), a menu selection,a command-line input, etc. Client computer 104 communicates the userrequest to server computer 102 (step 304), such as by sending a messageto server computer 102.

Server computer 102, upon receipt of the request, accesses themultimedia file corresponding to the request and provides the skimminglevel information regarding the multimedia content to client computer104 (step 306). Client computer 104 presents the skimming levelinformation to the user (step 308). Based on the presented information,the user can select one of the skimming levels. Client computer 104receives the skimming level selection ('step 310) and communicates theselection to server computer 102 (step 312).

Server computer 102, upon receipt of the skimming level selection,accesses the skimming information and generates the playlist for theselected skimming level (step 314). Alternatively, the playlist could begenerated by client computer 104 as discussed above with reference toFIG. 7. Server computer 102 then provides the segments of the multimediacontent that are identified by the playlist generated in step 314 toclient computer 104 (step 316). These segments are received by clientcomputer 104, which in turn presents the segments to the user (step318).

Various optimizations may also be implemented to improve the quality ofthe presentation of the multimedia content when streaming the segmentsof the multimedia content identified by a playlist to client computer104. One such optimization is pre-buffering of the multimedia content atclient computer 104. Subsequent segments of multimedia content can bebuffered at client computer 104 while current segments are beingpresented to the user. Thus, client computer 104 can seamlessly switchfrom presentation of the current segments to presentation of the nextsegments in the playlist.

Additionally, multimedia content may be streamed as multiple frames,including independent frames and dependent frames. Independent framesinclude all of the information necessary to present (e.g., display videoor play audio) a frame (or sample) of data, while dependent framesidentify only differences between the dependent frame and one or moreprevious frames (either dependent or independent). Playlists may includesegments that begin at either independent frames or dependent frames. Ifthe beginning of a segment is at a dependent frame, then additionalinformation prior to the beginning of that segment is needed in order togenerate the appropriate data for the dependent frame.

This situation can be resolved in a variety of different manners. In oneimplementation, the additional information (e.g., the previousindependent frame and possibly intervening dependent frames) istransmitted from server computer 102 to client computer 104. This canresult in a noticeable pause to the user while the additionalinformation is processed. In another implementation, if the beginningpoints for segments are known in advance, additional “specialized”independent frames can be generated as necessary in advance that includethe necessary additional information. In this implementation, thespecialized independent frame is transmitted to client computer 104along with the first dependent frame of the segment, thereby alleviatingclient computer 104 from having to process additional information spreadover potentially numerous independent and dependent frames.

FIG. 9 is a flowchart illustrating exemplary steps in changing skimminglevels in accordance with the invention. The steps of FIG. 9 areimplemented by server computer 102, and may be performed in software.Alternatively, steps 332-338 could be implemented by client computer104. FIG. 9 is described with additional reference to components in FIG.6.

Initially, server computer 102 receives an indication of a new skimminglevel request (step 332). Upon receipt of the indication, servercomputer 102 generates a playlist for the newly selected skimming level(step 334). Server computer 102 then identifies the current location inthe current playlist that is being presented to the user (step 336).Using this current location, server computer 102 determines thecorresponding location in the playlist for the new skimming level (step338). Server computer 102 then determines the start location within thenew playlist (step 340). Server computer then provides the segments ofthe multimedia content identified by the new playlist to the clientcomputer beginning at the start location (step 342).

In the illustrated embodiment, the start location within the newplaylist determined in step 340 is the beginning of the segmentcorresponding to the location identified in step 338. For example, ifthe user requests a new skimming level at a presentation time thatcorresponds to five seconds into the seventh segment of the newplaylist, then the start location is determined in step 340 to be thebeginning of the seventh segment of the new playlist. Alternatively, thestart location could be determined in step 340 to be five seconds intothe seventh segment of the new playlist.

User Experience

FIG. 10 shows one implementation of a graphical user interface window352 that displays multimedia content at a client computer 104 of FIG. 1.The user interface 352 is provided by multimedia player 280 of FIG. 6 orFIG. 7. The UI window 352 includes a video screen 354, a graphics screen356, and a text screen 358.

Video screen 354 is the region of the UI within which the video portionof the multimedia content is rendered. If the multimedia content doesnot include video data, screen 354 displays static or dynamic imagesrepresenting the content. For audio content, for example, a dynamicallychanging frequency wave that represents an audio signal can be displayedin screen 354.

Graphics screen 356 is the region of the UI within which the graphicsportion of the multimedia content is rendered. The graphics portion caninclude, for example, a set of slides or presentation foils thatcorrespond to the video portion. If the multimedia content does notinclude graphics data, then the graphics screen 356 is left blank (or anindication given that no graphics are available).

Text screen 358 is the region of the UI within which the text portion ofthe multimedia content is rendered. The text portion can include, forexample, a table of contents that outlines the multimedia content. Ifthe multimedia content does not include text data, then the text screen358 is left blank (or an indication given that no graphics areavailable).

The UI window 352 also includes a command bar 360, shuttle controls 362,a volume control 364, summary level selectors 366, 368, and 370, andcontent information space 372. Command bar 360 lists familiar UIcommands, such as “File”, “View”, and so forth.

Shuttle controls 362 allow the user to control playback of themultimedia content. Shuttle controls 362 include a stop button, a pausebutton, rewind buttons, a play button, and fast forward buttons.Selection of the fast forward (or rewind buttons) cause the multimediaplayer to jump ahead or back in the media presentation by apredetermined amount (e.g., one second, five seconds, to the nextsegment, etc.). The play, stop, and pause buttons cause theirconventional functions to be performed by media player 280.

Three different summary buttons 366, 368, and 370 are includedcorresponding to different summary levels. Selection of summary button366 causes multimedia player 280 to present a skimmed version of themultimedia content having a first level of detail to the user.Similarly, selection of summary button 368 causes multimedia player 280to present a skimmed version of the multimedia content having a secondlevel of detail, while selection of summary button 370 causes multimediaplayer 280 to present a skimmed version of the multimedia content havinga third level of detail.

The user can actuate one of the summary buttons 366-370 via a UIactuation mechanism, such as a pointer or by tabbing to the desired playbutton and hitting the “enter” key. Upon selection of a summary button,the multimedia player presents the skimmed version of the multimediacontent corresponding to the selected skimming level.

Similarly, the user can actuate any of the buttons of the shuttlecontrols 362 via a UI actuation mechanism, such as a pointer or bytabbing to the desired play button and hitting the “enter” key. Uponselection of a button, the multimedia player performs the requestedaction (e.g., stops or pauses playback, rewinds, etc.).

Volume control 364 allows the user to adjust the volume of the audioportion of the multimedia content.

Content information space 372 lists information pertaining to themultimedia content being rendered on the screens 354-358. The contentinformation space includes the show name, author and copyrightinformation, and tracking/timing data.

FIG. 11 shows another implementation of a graphical user interfacewindow that displays multimedia content at a client computer 104 ofFIG. 1. The user interface 382 is provided by multimedia player 280 ofFIG. 6 or FIG. 7.

Many of the components of UI window 382 are analogous to those of UIwindow 352 of FIG. 10. Like UI window 352 of FIG. 10, UI window 382includes a video screen 384, a graphics screen 386, a text screen 388, acommand bar 390, shuttle controls 392, a volume control 394, and contentinformation space 396. Each of these is analogous to the correspondingcomponents of UI 352 of FIG. 10.

UI 382 also has a menu 398 associated with skimming button 400. In thisillustration, menu 398 is a drop-down or pull-down menu that opensbeneath skimming button 400 in response to actuation of a tab 402.Alternatively, menu 398 may be invoked by placing a pointer overskimming button 400 and right clicking a mouse button.

Menu 398 lists multiple skimming levels from which a user can select. Inthe illustrated example, five skimming levels are listed: level 1 (15minute it presentation duration), level 2 (30 minute presentationduration), level 3 (45 minute presentation duration), level 4 (1 hourpresentation duration), and level 5 (1½ hours presentation time). Theuser can select one of the listed skimming levels to instruct themultimedia player to present the corresponding preview content. The usercan select a new skimming level after the multimedia player has begunpresentation by invoking the menu and selecting the new level. Inresponse, the multimedia player presents a new skimmed versioncorresponding to the new skimming level.

FIGS. 10 and 11 are merely exemplary illustrations of user interfacesvia which a user can select a skimming level. Alternatively, otherinterfaces could be used via which the user can change the skimminglevel, such as a rotatable dial, a sliding scale, an alphanumeric inputcontrol (e.g., allowing the user to type in a number, letter, or word),etc.

Conclusion

The invention provides multi-level skimming of multimedia content usingplaylist. A playlist for a skimmed version of the multimedia content isgenerated from skimming information maintained along with the multimediacontent. The skimming information advantageously identifies segments ofthe multimedia content, thereby conserving storage space by eliminatingthe need to duplicate storage of the actual segments.

Although the invention has been described in language specific tostructural features and/or methodological steps, it is to be understoodthat the invention defined in the appended claims is not necessarilylimited to the specific features or steps described. Rather, thespecific features and steps are disclosed as preferred forms ofimplementing the claimed invention.

1. A system for providing a skimmed version of multimedia content, thesystem comprising: means for accessing first skimming informationcorresponding to a first skimming level of a plurality of previouslygenerated skimming levels of the multimedia content; means for using thefirst skimming information to access a first plurality of segments ofthe multimedia content that correspond to the first skimming level;means for forwarding the first plurality of segments to a clientcomputer; means for receiving a selection of a second skimming level ofthe plurality of previously generated skimming levels from the clientcomputer while the first plurality of segments are being forwarded tothe client computer; means for accessing second skimming informationcorresponding to the second skimming level; means for using the secondskimming information to access a second plurality of segments of themultimedia content that correspond to the second skimming level; andmeans for forwarding the second plurality of segments to the clientcomputer:
 2. A system as recited in claim 1, wherein the means forforwarding the first plurality of segments comprises means for streamingthe accessed first plurality of segments to the client computer.
 3. Asystem as recited in claim 1, wherein the means for using the firstskimming information comprises means for generating a playlist based onthe first skimming information.
 4. A system as recited in claim 1,wherein the means for receiving further comprises means for receiving anindication of a current presentation time of the first plurality ofsegments.
 5. A system as recited in claim 4, wherein the indicationcomprises the presentation time referenced to the timeline of themultimedia content.
 6. A system as recited in claim 4, wherein theindication comprises a current segment of the first plurality ofsegments and an offset into the current segment.
 7. A system as recitedin claim 1, wherein the means for forwarding the second plurality ofsegments comprises: means for identifying a current presentation time ofthe first plurality of segments; means for identifying a time in thesecond plurality of segments that corresponds to the currentpresentation time; and means for forwarding the second plurality ofsegments to the client computer starting with the time in the secondplurality of segments that corresponds to the current presentation timeof the first plurality of segments.
 8. A system for presenting a skimmedversion of multimedia content, the system comprising: means foraccessing first skimming information corresponding to a first skimminglevel of a plurality of previously generated skimming levels of themultimedia content; means for using the first skimming information togenerate a playlist identifying a first plurality of segments of themultimedia content that correspond to the first skimming level; meansfor retrieving the first plurality of segments from a storage device;and means for presenting the first plurality of segments as the skimmedversion.
 9. A system as recited in claim 8, wherein the means forretrieving comprises: means for transmitting the playlist to a servercomputer; and means for receiving the first plurality of segments fromthe server computer.
 10. A system as recited in claim 8, furthercomprising: means for receiving user input identifying a second skimminglevel of the plurality of previously generated skimming levels while thefirst plurality of segments is being presented; means for accessingsecond skimming information corresponding to the second skimming level;means for using the second skimming information to generate a secondplaylist identifying a second plurality of segments of the multimediacontent that correspond to the second skimming level; means forretrieving the second plurality of segments from the storage device; andmeans for presenting the second plurality of segments as the skimmedversion.
 11. A system as recited in claim 10, wherein the means forretrieving the second plurality of segments comprises: means fortransmitting the second playlist to a server computer; and means forreceiving the second plurality of segments from the server computer. 12.A computer comprising: a processor; and a memory, coupled to theprocessor, storing instructions that, when executed by the processor,cause the processor to provide a skimmed version of multimedia contentby: accessing first skimming information corresponding to a firstskimming level of a plurality of previously generated skimming levels ofthe multimedia content; using the first skimming information to access afirst plurality of segments of the multimedia content that correspond tothe first skimming level; forwarding the first plurality of segments toa client computer; receiving a selection of a second skimming level ofthe plurality of previously generated skimming levels from the clientcomputer while the first plurality of segments are being forwarded tothe client computer; accessing second skimming information correspondingto the second skimming level; using the second skimming information toaccess a second plurality of segments of the multimedia content thatcorrespond to the second skimming level; and forwarding the secondplurality of segments to the client computer.
 13. A computer as recitedin claim 12, wherein the forwarding the first plurality of segmentscomprises streaming the accessed first plurality of segments to theclient computer.
 14. A computer as recited in claim 12, wherein theusing the first skimming information comprises generating a playlistbased on the first skimming information.
 15. A computer as recited inclaim 12, wherein the receiving further comprises receiving anindication of a current presentation time of the first plurality ofsegments.
 6. A computer as recited in claim 15, wherein the indicationcomprises the presentation time referenced to the timeline of themultimedia content.
 17. A computer as recited in claim 15, wherein theindication comprises a current segment of the first plurality ofsegments and an offset into the current segment.
 18. A computer asrecited in claim 12, wherein the forwarding of the second plurality ofsegments comprises: identifying a current presentation time of the firstplurality of segments; identifying a time in the second plurality ofsegments that corresponds to the current presentation time; andforwarding the second plurality of segments to the client computerstarting with the time in the second plurality of segments thatcorresponds to the current presentation time of the first plurality ofsegments.